Modulation of breast cancer cell viability by a cannabinoid receptor 2 agonist, JWH-015, is calcium dependent

Cannabinoids and triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) accounts for about 10-20% of all breast cancer cases and is associated with an unfavorable prognosis. Until recently, treatment options for TNBC were limited to chemotherapy. A new successful systemic treatment is immunotherapy with immune checkpoint inhibitors, but new tumor-specific biomarkers are needed to improve patient outcomes. Cannabinoids show antitumor activity in most preclinical studies in TNBC models and do not appear to have adverse effects on chemotherapy. Clinical data are needed to evaluate efficacy and safety in humans. Importantly, the endocannabinoid system is linked to the immune system and immunosuppression. Therefore, cannabinoid receptors could be a potential biomarker for immune checkpoint inhibitor therapy or a novel mechanism to reverse resistance to immunotherapy. In this article, we provide an overview of the currently available information on how cannabinoids may influence standard therapy in TNBC.

Melanoma and cannabinoids: A possible chance for cancer treatment

The endocannabinoid system is composed by a complex and ubiquitous network of endogenous lipid ligands, enzymes for their synthesis and degradation, and receptors, which can also be stimulated by exogenous compounds, such as those derived from the Cannabis sativa. Cannabis and its bioactive compounds, including cannabinoids and non-cannabinoids, have been extensively studied in different conditions. Recent data have shown that the endocannabinoid system is responsible for maintaining the homeostasis of various skin functions such as proliferation, differentiation and release of inflammatory mediators. Because of their role in regulating these key processes, cannabinoids have been studied for the treatment of skin cancers and melanoma; their anti-tumour effects regulate skin cancer progression and are mainly related to the inhibition of tumour growth, proliferation, invasion and angiogenesis, through apoptosis and autophagy induction. This review aims at summarising the current field of research on the potential uses of cannabinoids in the melanoma field.

Chronic Administration of Cannabinoid Receptor 2 Agonist (JWH-133) Increases Ectopic Ovarian Tumor Growth and Endocannabinoids (Anandamide and 2-Arachidonoyl Glycerol) Levels in Immunocompromised SCID Female Mice

Cannabinoid-based therapies are increasingly being used by cancer patients to treat chemotherapy-induced nausea and vomiting. Recently, cannabinoids have gained increased attention for their effects on cancer growth. Indeed, the effect of CB₂ (JWH-015, JWH-133) agonists on breast cancer models have shown to reduce the size of breast cancer tumors. However, these studies assessing breast cancer progression were using CB₂ agonist administered early into the cancer progression therefore assessing their effects on already established tumors is a critical need. In our study, we evaluate tumor growth using an ectopic xenograft ovarian (SKOV-3 and OVCAR-5) cancer model. The impact of chronic (30 days) administration of CB₂ (JWH-133) agonist will be evaluated and started on 30 days of ectopic ovarian tumors. We will then evaluate and determine the mechanisms involved in ovarian cancer tumor growth by measuring levels of anandamide and 2-arachidonoyl glycerol as well as protein levels of CB₁, CB₂, ERα, ERβ, GPER, TNFα, IL-1β and IL-6 in ovarian and tumor tissues. Our results demonstrate a significant increase in ectopic ovarian tumor growth following chronic administration of JWH-133. Ovarian cancer tumor tissues chronically (30 days) treated with JWH-133 in comparison to vehicle treated groups showed an increase in endocannabinoid (AEA and 2-AG) and protein (CB₂ and TNFα) levels with a decrease in GPER protein levels. Interestingly, our study emphasizes the importance of studying the impact of cannabinoid compounds on already established tumors to improve our understanding of cannabinoid-based therapies and, therefore better address clinical needs in cancer patients.

Endocannabinoid System and Tumour Microenvironment: New Intertwined Connections for Anticancer Approaches

The tumour microenvironment (TME) is now recognised as a hallmark of cancer, since tumour:stroma crosstalk supports the key steps of tumour growth and progression. The dynamic co-evolution of the tumour and stromal compartments may alter the surrounding microenvironment, including the composition in metabolites and signalling mediators. A growing number of evidence reports the involvement of the endocannabinoid system (ECS) in cancer. ECS is composed by a complex network of ligands, receptors, and enzymes, which act in synergy and contribute to several physiological but also pathological processes. Several in vitro and in vivo evidence show that ECS deregulation in cancer cells affects proliferation, migration, invasion, apoptosis, and metastatic potential. Although it is still an evolving research, recent experimental evidence also suggests that ECS can modulate the functional behaviour of several components of the TME, above all the immune cells, endothelial cells and stromal components. However, the role of ECS in the tumour:stroma interplay remains unclear and research in this area is particularly intriguing. This review aims to shed light on the latest relevant findings of the tumour response to ECS modulation, encouraging a more in-depth analysis in this field. Novel discoveries could be promising for novel anti-tumour approaches, targeting the microenvironmental components and the supportive tumour:stroma crosstalk, thereby hindering tumour development.

The Current and Potential Application of Medicinal Cannabis Products in Dentistry

Oral and dental diseases are a major global burden, the most common non-communicable diseases (NCDs), and may even affect an individual's general quality of life and health. The most prevalent dental and oral health conditions are tooth decay (otherwise referred to as dental caries/cavities), oral cancers, gingivitis, periodontitis, periodontal (gum) disease, Noma, oro-dental trauma, oral manifestations of HIV, sensitive teeth, cracked teeth, broken teeth, and congenital anomalies such as cleft lip and palate. Herbs have been utilized for hundreds of years in traditional Chinese, African and Indian medicine and even in some Western countries, for the treatment of oral and dental conditions including but not limited to dental caries, gingivitis and toothaches, dental pulpitis, halitosis (bad breath), mucositis, sore throat, oral wound infections, and periodontal abscesses. Herbs have also been used as plaque removers (chew sticks), antimicrobials, analgesics, anti-inflammatory agents, and antiseptics. Cannabis sativa L. in particular has been utilized in traditional Asian medicine for tooth-pain management, prevention of dental caries and reduction in gum inflammation. The distribution of cannabinoid (CB) receptors in the mouth suggest that the endocannabinoid system may be a target for the treatment of oral and dental diseases. Most recently, interest has been geared toward the use of Cannabidiol (CBD), one of several secondary metabolites produced by C. sativa L. CBD is a known anti-inflammatory, analgesic, anxiolytic, anti-microbial and anti-cancer agent, and as a result, may have therapeutic potential against conditions such burning mouth syndrome, dental anxiety, gingivitis, and possible oral cancer. Other major secondary metabolites of C. sativa L. such as terpenes and flavonoids also share anti-inflammatory, analgesic, anxiolytic and anti-microbial properties and may also have dental and oral applications. This review will investigate the potential of secondary metabolites of C. sativa L. in the treatment of dental and oral diseases.

Cannabinoids in the landscape of cancer

INTRODUCTION

Cannabinoids are a group of terpenophenolic compounds derived from the Cannabis sativa L. plant. There is a growing body of evidence from cell culture and animal studies in support of cannabinoids possessing anticancer properties.

METHOD

A database search of peer reviewed articles published in English as full texts between January 1970 and April 2021 in Google Scholar, MEDLINE, PubMed and Web of Science was undertaken. References of relevant literature were searched to identify additional studies to construct a narrative literature review of oncological effects of cannabinoids in pre-clinical and clinical studies in various cancer types.

RESULTS

Phyto-, endogenous and synthetic cannabinoids demonstrated antitumour effects both in vitro and in vivo. However, these effects are dependent on cancer type, the concentration and preparation of the cannabinoid and the abundance of receptor targets. The mechanism of action of synthetic cannabinoids, (-)-trans-Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) has mainly been described via the traditional cannabinoid receptors; CB1 and CB2, but reports have also indicated evidence of activity through GPR55, TRPM8 and other ion channels including TRPA1, TRPV1 and TRPV2.

CONCLUSION

Cannabinoids have shown to be efficacious both as a single agent and in combination with antineoplastic drugs. These effects have occurred through various receptors and ligands and modulation of signalling pathways involved in hallmarks of cancer pathology. There is a need for further studies to characterise its mode of action at the molecular level and to delineate efficacious dosage and route of administration in addition to synergistic regimes.

Pros and Cons of the Cannabinoid System in Cancer: Focus on Hematological Malignancies

The endocannabinoid system (ECS) is a composite cell-signaling system that allows endogenous cannabinoid ligands to control cell functions through the interaction with cannabinoid receptors. Modifications of the ECS might contribute to the pathogenesis of different diseases, including cancers. However, the use of these compounds as antitumor agents remains debatable. Pre-clinical experimental studies have shown that cannabinoids (CBs) might be effective for the treatment of hematological malignancies, such as leukemia and lymphoma. Specifically, CBs may activate programmed cell death mechanisms, thus blocking cancer cell growth, and may modulate both autophagy and angiogenesis. Therefore, CBs may have significant anti-tumor effects in hematologic diseases and may synergistically act with chemotherapeutic agents, possibly also reducing chemoresistance. Moreover, targeting ECS might be considered as a novel approach for the management of graft versus host disease, thus reducing some symptoms such as anorexia, cachexia, fatigue, anxiety, depression, and neuropathic pain. The aim of the present review is to collect the state of the art of CBs effects on hematological tumors, thus focusing on the essential topics that might be useful before moving into the clinical practice.

Molecular Mechanism of Cannabinoids in Cancer Progression

Cannabinoids are a family of heterogeneous compounds that mostly interact with receptors eliciting several physiological effects both in the central and peripheral nervous systems and in peripheral organs. They exert anticancer action by modulating signaling pathways involved in cancer progression; furthermore, the effects induced by their use depend on both the type of tumor and their action on the components of the endocannabinoid system. This review will explore the mechanism of action of the cannabinoids in signaling pathways involved in cancer proliferation, neovascularisation, migration, invasion, metastasis, and tumor angiogenesis.

Targeting Cannabinoid Receptors: Current Status and Prospects of Natural Products

Cannabinoid receptors (CB1 and CB2), as part of the endocannabinoid system, play a critical role in numerous human physiological and pathological conditions. Thus, considerable efforts have been made to develop ligands for CB1 and CB2, resulting in hundreds of phyto- and synthetic cannabinoids which have shown varying affinities relevant for the treatment of various diseases. However, only a few of these ligands are clinically used. Recently, more detailed structural information for cannabinoid receptors was revealed thanks to the powerfulness of cryo-electron microscopy, which now can accelerate structure-based drug discovery. At the same time, novel peptide-type cannabinoids from animal sources have arrived at the scene, with their potential in vivo therapeutic effects in relation to cannabinoid receptors. From a natural products perspective, it is expected that more novel cannabinoids will be discovered and forecasted as promising drug leads from diverse natural sources and species, such as animal venoms which constitute a true pharmacopeia of toxins modulating diverse targets, including voltage- and ligand-gated ion channels, G protein-coupled receptors such as CB1 and CB2, with astonishing affinity and selectivity. Therefore, it is believed that discovering novel cannabinoids starting from studying the biodiversity of the species living on planet earth is an uncharted territory.

Cannabinoids and Hormone Receptor-Positive Breast Cancer Treatment

Breast cancer (BC) is the most common cancer in women worldwide. Approximately 70–80% of BCs express estrogen receptors (ER), which predict the response to endocrine therapy (ET), and are therefore hormone receptor-positive (HR+). Endogenous cannabinoids together with cannabinoid receptor 1 and 2 (CB1, CB2) constitute the basis of the endocannabinoid system. Interactions of cannabinoids with hypothalamic–pituitary–gonadal axis hormones are well documented, and two studies found a positive correlation between peak plasma endogenous cannabinoid anandamide with peak plasma 17β-estradiol, luteinizing hormone and follicle-stimulating hormone levels at ovulation in healthy premenopausal women. Do cannabinoids have an effect on HR+ BC? In this paper we review known and possible interactions between cannabinoids and specific HR+ BC treatments. In preclinical studies, CB1 and CB2 agonists (i.e., anandamide, THC) have been shown to inhibit the proliferation of ER positive BC cell lines. There is less evidence for antitumor cannabinoid action in HR+ BC in animal models and there are no clinical trials exploring the effects of cannabinoids on HR+ BC treatment outcomes. Two studies have shown that tamoxifen and several other selective estrogen receptor modulators (SERM) can act as inverse agonists on CB1 and CB2, an interaction with possible clinical consequences. In addition, cannabinoid action could interact with other commonly used endocrine and targeted therapies used in the treatment of HR+ BC.

The Endocannabinoid System Alleviates Pain in a Murine Model of Cancer-Induced Bone Pain

Metastatic breast cancer is prevalent worldwide, and one of the most common sites of metastasis is long bones. Of patients with disease, the major symptom is pain, yet current medications fail to adequately result in analgesic efficacy and present major undesirable adverse effects. In our study, we investigate the potential of a novel monoacylglycerol lipase (MAGL) inhibitor, MJN110, in a murine model of cancer-induced bone pain. Literature has previously demonstrated that MAGL inhibitors function to increase the endogenous concentrations of 2-arachydonylglycerol, which then activates CB1 and CB2 receptors to inhibit inflammation and pain. We demonstrate that administration of MJN110 significantly and dose dependently alleviates spontaneous pain behavior during acute administration compared with vehicle control. In addition, MJN110 maintains its efficacy in a chronic-dosing paradigm over the course of 7 days without signs of receptor sensitization. In vitro analysis of MJN110 demonstrated a dose-dependent and significant decrease in cell viability and proliferation of 66.1 breast adenocarcinoma cells to a greater extent than KML29, an alternate MAGL inhibitor, or the CB2 agonist JWH015. Chronic administration of the compound did not appear to affect tumor burden, as evidenced by radiograph or histologic analysis. Together, these data support the application for MJN110 as a novel therapeutic for cancer-induced bone pain. SIGNIFICANCE STATEMENT: Current standard of care for metastatic breast cancer pain is opioid-based therapies with adjunctive chemotherapy, which have highly addictive and other deleterious side effects. The need for effective, non-opioid-based therapies is essential, and harnessing the endogenous cannabinoid system is proving to be a new target to treat various types of pain conditions. We present a novel drug targeting the endogenous cannabinoid system that is effective at reducing pain in a mouse model of metastatic breast cancer to bone.

Antitumor Cannabinoid Chemotypes: Structural Insights

Cannabis has long been known to limit or prevent nausea and vomiting, lack of appetite, and pain. For this reason, cannabinoids have been successfully used in the treatment of some of the unwanted side effects caused by cancer chemotherapy. Besides their palliative effects, research from the past two decades has demonstrated their promising potential as antitumor agents in a wide variety of tumors. Cannabinoids of endogenous, phytogenic, and synthetic nature have been shown to impact the proliferation of cancer through the modulation of different proteins involved in the endocannabinoid system such as the G protein-coupled receptors CB1, CB2, and GRP55, the ionotropic receptor TRPV1, or the fatty acid amide hydrolase (FAAH). In this article, we aim to structurally classify the antitumor cannabinoid chemotypes described so far according to their targets and types of cancer. In a drug discovery approach, their in silico pharmacokinetic profile has been evaluated in order to identify appropriate drug-like profiles, which should be taken into account for further progress toward the clinic. This analysis may provide structural insights into the selection of specific cannabinoid scaffolds for the development of antitumor drugs for the treatment of particular types of cancer.

Modulation of the Endocannabinoid System as a Potential Anticancer Strategy

Currently, the involvement of the endocannabinoid system in cancer development and possible options for a cancer-regressive effect of cannabinoids are controversially discussed. In recent decades, a number of preclinical studies have shown that cannabinoids have an anticarcinogenic potential. Therefore, especially against the background of several legal simplifications with regard to the clinical application of cannabinoid-based drugs, an extended basic knowledge about the complex network of the individual components of the endocannabinoid system is required. The canonical endocannabinoid system consists of the endocannabinoids N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol as well as the G_i/o protein-coupled transmembrane cannabinoid receptors CB₁ and CB₂. As a result of extensive studies on the broader effect of these factors, other fatty acid derivatives, transmembrane and intracellular receptors, enzymes and lipid transporters have been identified that contribute to the effect of endocannabinoids when defined in the broad sense as “extended endocannabinoid system.” Among these additional components, the endocannabinoid-degrading enzymes fatty acid amide hydrolase and monoacylglycerol lipase, lipid transport proteins of the fatty acid-binding protein family, additional cannabinoid-activated G protein-coupled receptors such as GPR55, members of the transient receptor family, and peroxisome proliferator-activated receptors were identified as targets for possible strategies to combat cancer progression. Other endocannabinoid-related fatty acids such as 2-arachidonoyl glyceryl ether, O-arachidonoylethanolamine, N-arachidonoyldopamine and oleic acid amide showed an effect via cannabinoid receptors, while other compounds such as endocannabinoid-like substances exert a permissive action on endocannabinoid effects and act via alternative intracellular target structures. This review gives an overview of the modulation of the extended endocannabinoid system using the example of anticancer cannabinoid effects, which have been described in detail in preclinical studies.

MDA19, a novel CB2 agonist, inhibits hepatocellular carcinoma partly through inactivation of AKT signaling pathway

BACKGROUND

CB2 (cannabinoid receptor 2) agonists have been shown to exert anti-tumor activities in different tumor types. However, there is no study exploring the role of MDA19 (a novel CB2 agonist) in tumors. In this study we aimed to investigate the effects of MDA19 treatment on HCC cell lines, Hep3B and HepG2 and determine the relevant mechanisms.

RESULTS

Cell proliferation analysis, including CCK8 and colony formation assays, indicated that MDA19 treatment inhibited HCC cell proliferation in a dose- and time-dependent manner. Flow cytometry suggested that MDA19 induced cell apoptosis and activation of mitochondrial apoptosis pathway. Transwell assay indicated that HCC cell migration and invasion were significantly inhibited by MDA19 treatment. Mechanism investigation suggested that MDA19 induced inactivation of AKT signaling pathway in HCC cells. In addition, we investigated the function of CB2receptor in HCC and its role in the anti-tumor activity of MDA19. By searching on Kaplan-Meier plotter ( http://kmplot.com/analysis/ ), we found that HCC patients with high CB2 expression had a better survival and CB2 expression was significantly associated with gender, clinical stages and race of HCC patients (P < 0.05). CB2 inhibited the progression of HCC cells and its knockdown could rescue the growth inhibition induced by MDA19 in HCC. Moreover, the inhibitory effect of MDA19 on AKT signaling pathway was also reversed by CB2 knockdown.

CONCLUSION

Our data suggest that MDA-19 exerts an anti-tumor activity at least partly through inactivation of AKT signaling pathway in HCC. CB2 functions as a tumor suppressor gene in HCC, and MDA19-induced growth inhibition of HCC cells depends on its binding to CB2 to activate it. MDA-19 treatment may be a promising strategy for HCC therapy.

REVIEWER

This article was reviewed by Tito Cali, Mohamed Naguib and Bo Chen.

Cannabinoids in cancer treatment: Therapeutic potential and legislation

The plant Cannabis sativa L. has been used as an herbal remedy for centuries and is the most important source of phytocannabinoids. The endocannabinoid system (ECS) consists of receptors, endogenous ligands (endocannabinoids) and metabolizing enzymes, and plays an important role in different physiological and pathological processes. Phytocannabinoids and synthetic cannabinoids can interact with the components of ECS or other cellular pathways and thus affect the development/progression of diseases, including cancer. In cancer patients, cannabinoids have primarily been used as a part of palliative care to alleviate pain, relieve nausea and stimulate appetite. In addition, numerous cell culture and animal studies showed antitumor effects of cannabinoids in various cancer types. Here we reviewed the literature on anticancer effects of plant-derived and synthetic cannabinoids, to better understand their mechanisms of action and role in cancer treatment. We also reviewed the current legislative updates on the use of cannabinoids for medical and therapeutic purposes, primarily in the EU countries. In vitro and in vivo cancer models show that cannabinoids can effectively modulate tumor growth, however, the antitumor effects appear to be largely dependent on cancer type and drug dose/concentration. Understanding how cannabinoids are able to regulate essential cellular processes involved in tumorigenesis, such as progression through the cell cycle, cell proliferation and cell death, as well as the interactions between cannabinoids and the immune system, are crucial for improving existing and developing new therapeutic approaches for cancer patients. The national legislation of the EU Member States defines the legal boundaries of permissible use of cannabinoids for medical and therapeutic purposes, however, these legislative guidelines may not be aligned with the current scientific knowledge.